How long do animals carry MRSP/MRSI?

I’ve had this question a lot lately. Methicillin-resistant Staphylococcus pseudintermedius (MRSP), which is sometimes misidentified as methicillin-resistant S. intermedius (MRSI), is an important and increasing cause of infections in dogs and cats. After an animal has had an MRSP/MRSI infection, a question people often ask is how long they will carry the bacterium?

MRSP can be carried in the nose, intestinal tract or on the skin of a small percentage of normal animals. The implications of this are not clear, but it is reasonable to assume that carriers are more likely to develop infections in certain situations (e.g. if they sustain a wound or need to have surgery), and can transmit it to other animals (and possibly people, but that’s much less of a concern with MRSP than with MRSA).

Back to the question… To be perfectly honest, we really don’t know. However, I think it’s reasonable to assume that some animals could carry MRSP for a long period of time – certainly weeks or months, maybe even years. Staphylococcu pseudintermedius is a common bacterium in healthy dogs and cats, and has basically evolved to survive on these animals. The methicillin-resistant versions are likely no different in this respect, so it’s reasonable to assume that some animals could be long-term carriers. This makes controlling MRSP more difficult. In contrast, MRSA appears to be only transiently carried by dogs and cats, probably because it is better adapted to living on humans than pets.

About This Blog

Worms & Germs Blog is an educational website coordinated by Drs. Scott Weese and Maureen Anderson of the Ontario Veterinary College’s Centre for Public Health and Zoonoses. The site was initially set up with the help of funding from City…

About

The Centre for Public Health and Zoonoses offers information relating to zoonotic diseases (diseases transmitted from animals to people), including aspects of human and pet health, infection prevention and control, and vaccination. It is located at the University of Guelph, in Ontario, Canada.